GPVS.f File Reference

gpvs() computes saturation vapor pressure table. More...

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Functions/Subroutines
real function	FPVS (T)
real function	FPVS0 (T, NX, C1XPVS0, C2XPVS0, TBPVS0)
real function	FPVSX (T)
real function	FPVSX0 (T)
subroutine	GPVS

Detailed Description

gpvs() computes saturation vapor pressure table.

Compute saturation vapor pressure table as a function of temperature for the table lookup function FPVS. Exact saturation vapor pressures are calculated in subprogram FPVSX. The current implementation computes a table with a length of 7501 for temperatures ranging from 180.0 to 330.0 Kelvin.

Parameters

[out]

pvu

real (km) potential vorticity (10**-6*K*m**2/kg/s).

Program History Log

Date	Programmer	Comments
1982-12-30	N Phillips	Initial
1991-05-07	Mark Iredell	Made into inlinable function
1994-12-30	Mark Iredell	Expand table
1996-02-19	Hong	Ice effect

Note

Lookup tables for the saturation vapor pressure w/r/t water & ice.

Author

N Phillips W/NP2

Date

1982-12-30

Definition in file GPVS.f.

Function/Subroutine Documentation

real function FPVS

(

real

T

)

Parameters

t	fpvs() computes saturation vapor pressure.

Compute saturation vapor pressure from the temperature. A linear interpolation is done between values in a lookup table computed in GPVS. See documentation for FPVSX for details. Input values outside table range are reset to table extrema. The interpolation accuracy is almost 6 decimal places. On the CRAY, FPVS is about 4 times faster than exact calculation. This function should be expanded inline in the calling routine.

Parameters

[in]	T	real temperature in Kelvin.
[out]	FPVS	real saturation vapor pressure in kilopascals (CB).

Program History Log

Date	Programmer	Comments
1982-12-30	N Phillips	Initial
1991-05-07	Mark Iredell	Made into inlinable function
1994-12-30	Mark Iredell	Expand table
1996-02-19	Hong	Ice effect

Author

N Phillips W/NP2

Date

1982-12-30

Definition at line 54 of file GPVS.f.

real function FPVSX

(

real

T

)

fpvsx() computes saturation vapor pressure.

Exactly compute saturation vapor pressure from temperature. The water model assumes a perfect gas, constant specific heats for gas and liquid, and neglects the volume of the liquid. The model does account for the variation of the latent heat of condensation with temperature. The ice option is not included. The Clausius-Clapeyron equation is integrated from the triple point To get the formula

PVS=PSATK*(TR**XA)*exp(XB*(1.-TR))

where TR is TTP/T and other values are physical constants This function should be expanded inline in the calling routine.

Parameters

[in]	T	real temperature in Kelvin.
[out]	FPVSX	real saturation vapor pressure in kilopascals (CB).

Program History Log

Date	Programmer	Comments
1982-12-30	N Phillips	Initial
1991-05-07	Mark Iredell	Made into inlinable function
1994-12-30	Mark Iredell	Exact computation
1996-02-19	Hong	Ice effect

Author

N Phillips W/NP2

Date

1982-12-30

Definition at line 121 of file GPVS.f.